Arrangement in heat exchangers of the plate type



May 20, 1969 P. E. R. STALBERG ARRANGEMENT IN HEAT EXCHANGERS OF THE PLATE TYPE Filed Nov. 28, 1967 Sheet May 20, 1969 P. E. R. STALBERG 3,444,926

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United States Patent 3,444,926 ARRANGEMENT 1N HEAT EXCHANGERS OF THE PLATE TYPE Per Erik Ruben Stalberg, Lingbo, Sweden, assignor to AB Rosenblads Patenter, Stockholm, Sweden, a corporation of Sweden Filed Nov. 28, 1967, Ser. No. 686,051 Int. Cl. F28f 3/08 US. Cl. 165166 1 Claim ABSTRACT OF THE DISCLOSURE A heat exchanger of the plate type in which sealing rings cooperate with clamps to provide an adjustable, uniform sealing pressure throughout is disclosed. Packing rings of hard sealing material extend around the periphery of the plates and inner packing rings surround through passages within the plate assembly. Independently adjustable clamps acting on the outer and inner series of sealing elements provide an even distribution of sealing pressure.

The present invention is concerned with heat exchangers of the plate type comprising a plurality of heat transfer plates made of thin sheet metal and detachably combined into an assembly in which spaces between the plates form through-passages for the heat exchanging fluids, the inlets and outlets of which each comprises a series of holes extending through the separate plates and disposed opposite to one another in the assembly.

In the embodiment of such heat exchangers now almost exclusively adopted the assembly comprises substantially rectangular plates presenting four series of through-holes or through-passages, one series through each corner portion of the plates. Situated together within the throughpassage in each space between the plates, viewed towards the plane of said plates, are two such series of holes (enclosed or internal series) and enclosed by an edge-packing which encircles said passage, while the two remaining series of holes (excluded or external series) situated outside the passage and the edge packing are each enclosed by a packing (hole packing) which seals the series against the associated interspacing; the internal and external series of holes in each alternate interspace being excluded and enclosed respectively, in the remaining interspaces.

As well-known, it is not possible in such an apparatus to arrange the paths or tracks for the packings in the various interspaces so that throughout the assembly said packings lie opposite to one another and mutually support one another when the said assembly is drawn together in conventional manner between rigid end plates. Consequently it cannot be avoided that the packings in each interspace must at least to some extent, extend between plate portions which without support of a packing in adjacent interspaces will yield and result in a lower sealing pressure than that between portions which have such a support. Thus, the sealing pressure is unevenly distributed over the sealing surfaces, whereby the lowest sealing pressure will cause an undesirable limitation of the inner pressure at which the heat exchanger can be used. Generally, therefore, it has been necessary to use relatively thick packings of sulficiently elastic material so that the abutment pressure between the yielding portions will not reduce too much. Practically the only type of material which can be used in this connection is various ice types of rubber, a factor which has caused the utility of the heat exchanger to be further restricted to the relatively low temperatures to which this material can be subjected without being impaired.

In the case of heat exchangers to be used for high pressure and/or high temperatures and when, at the same time, detachable plate assemblies are preferred it has hitherto been necessary in many cases, as a result of the aforementioned disadvantages, by choice or by necessity to ignore the advantages offered by such a plate assembly and to use instead a heat exchanger comprising entirely a welded plate assembly.

The primary object of this invention is to eliminate these disadvantages by providing a heat exchanger of a construction permitting the use of thin packings made of such material as Klingerit an asbestos gasket material manufactured by the H. F. White Company of Brooklyn, N.Y., or Teflon having the ability of resisting high pressure as well as high temperatures, thus making it possible to apply to all sealing surfaces the sealing pressure necessary, which may be higher than the pressure at which the remaining portions of the plates should suitably be maintained pressed against each other.

Another object of this invention is to provide a com pact and highly efiicient heat exchanger of the plate type.

A further object of this invention is to provide a readily disassemblable heat exchanger in which the sealing pressure of the elements is selectively adjustable.

Further objects and advantages of the invention will be apparent from the following detailed description and the accompanying drawings.

While based upon the previously known arrangement, wherein the interspace between the plates along the periphery thereof are sealed by means of insert rings, here called outer insert rings, comprising packing rings of thin material, and distance rings which together form an outer pile in the assembly, the invention is characterized by the combination that the through-holes are enclosed in a known manner by inner insert rings comprising second distance rings and second packing rings similarly of a thin packing material, which together, enclosed by the outer pile, form inner piles in the plate assembly, each pile being held together by clamping means, the outer pile per se being held together by clamping means spaced from said clamping means of the inner piles, while the plate assembly is held together between said piles by clamping means separated from the respective clamping means of the piles.

The invention will now be described in detail with reference to the accompanying drawing in which:

FIGURE 1 illustrates a heat exchanger according to the invention, in section viewed from the side along the line II in FIGURE 2;

FIGURE 2 illustrates the heat exchanger according to FIGURE 1, in section along line II-II in said figure;

FIGURE 3 illustrates the three uppermost heat transfer plates according to FIGURE 1, with intermediate details spaced vertically;

FIGURE 4 illustrates a section of a modified embodiment of the heat exchanger according to FIGURE 1, viewed from the side along line IVIV in FIGURE 5;

FIGURE 5 illustrates a section of the heat exchanger according to FIGURE 4, viewed along the line VV in said figure; and

FIGURE 6 illustrates the three uppermost heat transfer plates according to FIGURE 4, with intermediate details spaced vertically.

All figures are diagrammatic and are merely intended to illustrate examples without restriction. Identical elements in the Various figures are indicated by the same reference numerals.

In the heat exchanger according to FIGURES l, 2 and 3 the plate assembly comprises a number of completely fiat heat transferring plates 1 which all, except the uppermost, are provided with distance elements in the form of studs 2 which hold the plates in spaced relation so as to define alternating interspaces a and b between the plates. The distance elements may also comprise sections pressed out of the plate. Each interspace is outwardly sealed along the edge portions of the plates by means of three insert rings, here called outer insert rings, which comprise a distance ring 3 made of a rigid material, and on each side of said ring a packing ring 4 made of a thin packing material; the interspaces forming through-passages, viz a for one heat exchanging fluid and b for the other heat exchanging fiuid. Two series 5a and two series 5b of opposing through-holes 6 passing through the separate plates communicate with passages a and passages b respectively, and with a respective branch pipe for connection to external conduits for the heat exchanging media. Arranged around each such series of holes in each of the spaces between the plates, i.e. each through-passage there are insert rings, hereinafter called inner insert rings, which bridge the interspace and closely encircle the throughholes. In each interspace around a series of holes which shall not communicate with the interspace in question the inner insert rings comprise (1) a distance ring 8 made of a rigid material, (2) on each side of said ring 8 a packing ring 9 made of a thin packing material, as well as (3) a distance ring 8a around the series of holes which are to communicate with the interspace in question, said distance ring 8a being perforated with radially extending through-holes 10. It is not necessary that the packing rings lie in sealing abutment, but the distance ring 8a is instead higher than the distance ring 8 to an extent corresponding to the total thickness of the packing rings 9. Naturally, as an alternative the distance rings may be as high as the packing rings throughout. Thus, the series of holes 5a communicate via perforated distance rings 8a with the passages a which are closed by means of distance rings 8 with packings against the series of holes 5b, which instead in the same manner communicates with the passages b closed against the series of holes 5a.

According to the invention the outer insert rings 3 and 4 in the system described form together with the intermediate plate portions a pile which is held together between an end plate .11 and a flange 12 of a second end plate 13, by means of a number of bolt joints 14, by means of which said pile can be drawn together with optional pressure. Around each series of holes all inner insert rings 8, 8a and 9 form together with the intermediate plate portions, a pile which is held together between a washer 15 and the branch pipe 7 through bolt means '16, with which each such pile can similarly be tightened together per se at an optional pressure. Further, all packing portions are uniformally and rigidly supported. One particularly important feature is the possibility of applying sufiicient sealing pressure to each of the piles of inner insert rings, since this is a condition which allows the relatively simple system, wherein all series of holes are positioned within all through-passages, to be used without risk of leakage, which would result in the two heat exchanging fluids inter-mixing.

Similarly, according to the invention, the sections of the plate assembly located between respective piles, that is to say between the seals, are held together by means of the aforesaid end plate '11 and a special end plate 17 which is acted upon by set screws 18, threaded into the end plate 13. In this manner the plate assembly will be held together at these portions against internal pressure in the apparatus, without it being necessary to apply a pressure which l o is o serve as e i g p e u e vice vers to generate a sealing pressure which is restricted to that obtained when the plates in the assembly are drawn completely together.

In the heat exchanger according to FIGURES 4, 5 and 6 the heat transferring plates 1a are of a different design which, inter alia, affords a sipmlification of the insert ring system. In other respects the heat exchanger is substantially identical with that of FIGURES 1, 2 and 3.

The modification resides in that the plates around their outer edges and around their through-holes 6 are provided with planar sections '19 around the outer edges and 20 around the through-passages (FIGURE 5 and FIGURE 6), embossed over the basic level of the plate in such a way that, when the plates lie together, as in the plate assembly, in each alternate interspace a the adjacent plates around their edge sections and around two series 5b of opposed through-holes approach one another in such close proximity that the interspace can there be bridged by one thin packing only, i.e. packings 4 between the edge portions and packings 9 around the series of holes, while in the remaining interspaces b the plates around the remaining series of holes '5a approach each other in a similar manner. The plates are, furthermore on both sides provided with distance elements 2a, which fix the plates in such position.

If the two heat exchangers are now compared, particularly FIGURE 3 with FIGURE 6, it will thus be found that in the later case the distance ring 8 with two packing rings 9 in all interspaces a and b is replaced by one single packing ring 9 and in each alternate interspace a, furthermore, the distance ring 3 with two packing rings 4 is replaced by one single packing ring 4. The remaining distance rings, '3 in the interspace b and 8a in all interspaces, have only been designed with the greater height necessary to bridge the greater distance, caused by the changed design of the plates, between the plates at these places. The plate assembly constructed in this way can be produced by placing the identical plates 1a together so as to cover one another completely each alternate plate being rotated through around its centre line CC (FIGURE 5) in relation to the other plates.

What I claim is: v

1. An arrangement in heat exchangers of the separable plate type, having a plurality of heat transferring plates of thin sheet material arranged in side by side spaced relation so as to form a stack within which the interspaces between the plates define interplate flow-channels for heat exchanging media, every second such interspace communicating with an inlet and an outlet for a first heat exchanging medium via a first pair of series respectively of registering through-holes through the several plates and the remaining interspaces communicating with an inlet and an outlet for a second heat exchanging medium via a second pair of series respectively of such through-holes, said interspaces being sealed along the periphery of the plates by means of inserted first distance rings and first packing rings of thin hard packing material, said rings together forming an outer pile of rings in the stack, said registering through-holes in said interspaces being surrounded by second distance rings and second packing rings likewise of thin hard packing material, said second rings together forming an inner pile of rings around each series of registering through-holes within said outer pile of rings, said plates between said piles being spaced by further spacer elements in distributed position between the plates, said arrangement comprising the improvement that the stack of plates is clamped together between support members at one side of the stack and at the other side of the stack in combination, a first clamping member shaped to abut against the stack only in registering relation to said outer pile of rings, second clamping members shaped to abut against the stack only in registering relation to each of said inner piles of rings and a third clamping member shaped to cover the stack only between said outer and inner piles of rings, said first, second and third clamping members being arranged to be pressed individually against the stack by separate screw members.

References Cited UNITED STATES PATENTS 2,222,721 11/1940 Ramsaur et a] 1. 165165 6 2,617,634 11/1952 Jendrassik 165157 X 2,686,154 8/1954 MacNeill 210321 3,240,268 3/1966 Armes 165167 ROBERT A. OLEARY, Primary Examiner.

THEOPHIL W. STREULE, Assistant Examiner. 

